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Fulltext Cardiovascular risk scores do not account for the effect of treatment: a review

Liew SM, Doust J, Glasziou P

Heart, 2011 May;97(9):689-97.
PMID: 21474616 DOI: 10.1136/hrt.2010.220442

OBJECTIVE: To compare the strengths and limitations of cardiovascular risk scores available for clinicians in assessing the global (absolute) risk of cardiovascular disease.
DESIGN: Review of cardiovascular risk scores.
DATA SOURCES: Medline (1966 to May 2009) using a mixture of MeSH terms and free text for the keywords 'cardiovascular', 'risk prediction' and 'cohort studies'.
ELIGIBILITY CRITERIA FOR SELECTING STUDIES: A study was eligible if it fulfilled the following criteria: (1) it was a cohort study of adults in the general population with no prior history of cardiovascular disease and not restricted by a disease condition; (2) the primary objective was the development of a cardiovascular risk score/equation that predicted an individual's absolute cardiovascular risk in 5-10 years; (3) the score could be used by a clinician to calculate the risk for an individual patient.
RESULTS: 21 risk scores from 18 papers were identified from 3536 papers. Cohort size ranged from 4372 participants (SHS) to 1591209 records (QRISK2). More than half of the cardiovascular risk scores (11) were from studies with recruitment starting after 1980. Definitions and methods for measuring risk predictors and outcomes varied widely between scores. Fourteen cardiovascular risk scores reported data on prior treatment, but this was mainly limited to antihypertensive treatment. Only two studies reported prior use of lipid-lowering agents. None reported on prior use of platelet inhibitors or data on treatment drop-ins.
CONCLUSIONS: The use of risk-factor-modifying drugs-for example, statins-and disease-modifying medication-for example, platelet inhibitors-was not accounted for. In addition, none of the risk scores addressed the effect of treatment drop-ins-that is, treatment started during the study period. Ideally, a risk score should be derived from a population free from treatment. The lack of accounting for treatment effect and the wide variation in study characteristics, predictors and outcomes causes difficulties in the use of cardiovascular risk scores for clinical treatment decision.
Fulltext Cardiovascular risk scores: qualitative study of how primary care practitioners understand and use them

Liew SM, Blacklock C, Hislop J, Glasziou P, Mant D

Br J Gen Pract, 2013 Jun;63(611):e401-7.
PMID: 23735411 DOI: 10.3399/bjgp13X668195

BACKGROUND: The National Institute for Health and Care Excellence guidelines and the Quality Outcomes Framework require practitioners to use cardiovascular risk scores in assessments for the primary prevention of cardiovascular disease.
AIM: To explore GPs understanding and use of cardiovascular risk scores.
DESIGN AND SETTING: Qualitative study with purposive maximum variation sampling of 20 GPs working in Oxfordshire, UK. Method Thematic analysis of transcriptions of face-to-face interviews with participants undertaken by two individuals (one clinical, one non-clinical).
RESULTS: GPs use cardiovascular risk scores primarily to guide treatment decisions by estimating the risk of a vascular event if the patient remains untreated. They expressed considerable uncertainty about how and whether to take account of existing drug treatment or other types of prior risk modification. They were also unclear about the choice between the older scores, based on the Framingham study, and newer scores, such as QRISK. There was substantial variation in opinion about whether scores could legitimately be used to illustrate to patients the change in risk as a result of treatment. The overall impression was of considerable confusion.
CONCLUSION: The drive to estimate risk more precisely by qualifying guidance and promoting new scores based on partially-treated populations appears to have created unnecessary confusion for little obvious benefit. National guidance needs to be simplified, and, to be fit for purpose, better reflect the ways in which cardiovascular risk scores are currently used in general practice. Patients may be better served by simple advice to use a Framingham score and exercise more clinical judgement, explaining to patients the necessary imprecision of any individual estimate of risk.
Fulltext Should identical CVD risks in young and old patients be managed identically? Results from two models

Liew SM, Jackson R, Mant D, Glasziou P

BMJ Open, 2012;2(2):e000728.
PMID: 22382122 DOI: 10.1136/bmjopen-2011-000728

OBJECTIVES: To assess whether delaying risk reduction treatment has a different impact on potential life years lost in younger compared with older patients at the same baseline short-term cardiovascular risk.
DESIGN: Modelling based on population data.
METHODS: Potential years of life lost from a 5-year treatment delay were estimated for patients of different ages but with the same cardiovascular risk (either 5% or 10% 5-year risk). Two models were used: an age-based residual life expectancy model and a Markov simulation model. Age-specific case fatality rates and time preferences were applied to both models, and competing mortality risks were incorporated into the Markov model.
RESULTS: Younger patients had more potential life years to lose if untreated, but the maximum difference between 35 and 85 years was <1 year, when models were unadjusted for time preferences or competing risk. When these adjusters were included, the maximum difference fell to about 1 month, although the direction was reversed with older people having more to lose.
CONCLUSIONS: Surprisingly, age at onset of treatment has little impact on the likely benefits of interventions that reduce cardiovascular risk because of the opposing effects of life expectancy, case fatality, time preferences and competing risks. These findings challenge the appropriateness of recommendations to use lower risk-based treatment thresholds in younger patients.
Fulltext A randomised controlled trial of a blended learning education intervention for teaching evidence-based medicine

Ilic D, Nordin RB, Glasziou P, Tilson JK, Villanueva E

BMC Med Educ, 2015;15:39.
PMID: 25884717 DOI: 10.1186/s12909-015-0321-6

BACKGROUND: Few studies have been performed to inform how best to teach evidence-based medicine (EBM) to medical trainees. Current evidence can only conclude that any form of teaching increases EBM competency, but cannot distinguish which form of teaching is most effective at increasing student competency in EBM. This study compared the effectiveness of a blended learning (BL) versus didactic learning (DL) approach of teaching EBM to medical students with respect to competency, self-efficacy, attitudes and behaviour toward EBM.
METHODS: A mixed methods study consisting of a randomised controlled trial (RCT) and qualitative case study was performed with medical students undertaking their first clinical year of training in EBM. Students were randomly assigned to receive EBM teaching via either a BL approach or the incumbent DL approach. Competency in EBM was assessed using the Berlin questionnaire and the 'Assessing Competency in EBM' (ACE) tool. Students' self-efficacy, attitudes and behaviour was also assessed. A series of focus groups was also performed to contextualise the quantitative results.
RESULTS: A total of 147 students completed the RCT, and a further 29 students participated in six focus group discussions. Students who received the BL approach to teaching EBM had significantly higher scores in 5 out of 6 behaviour domains, 3 out of 4 attitude domains and 10 out of 14 self-efficacy domains. Competency in EBM did not differ significantly between students receiving the BL approach versus those receiving the DL approach [Mean Difference (MD)=-0.68, (95% CI-1.71, 0.34), p=0.19]. No significant difference was observed between sites (p=0.89) or by student type (p=0.58). Focus group discussions suggested a strong student preference for teaching using a BL approach, which integrates lectures, online learning and small group activities.
CONCLUSIONS: BL is no more effective than DL at increasing medical students' knowledge and skills in EBM, but was significantly more effective at increasing student attitudes toward EBM and self-reported use of EBM in clinical practice. Given the various learning styles preferred by students, a multifaceted approach (incorporating BL) may be best suited when teaching EBM to medical students. Further research on the cost-effectiveness of EBM teaching modalities is required.
Fulltext Development of a Search Strategy for an Evidence Based Retrieval Service

Ho GJ, Liew SM, Ng CJ, Hisham Shunmugam R, Glasziou P

PLoS One, 2016;11(12):e0167170.
PMID: 27935993 DOI: 10.1371/journal.pone.0167170

BACKGROUND: Physicians are often encouraged to locate answers for their clinical queries via an evidence-based literature search approach. The methods used are often not clearly specified. Inappropriate search strategies, time constraint and contradictory information complicate evidence retrieval.
AIMS: Our study aimed to develop a search strategy to answer clinical queries among physicians in a primary care setting.
METHODS: Six clinical questions of different medical conditions seen in primary care were formulated. A series of experimental searches to answer each question was conducted on 3 commonly advocated medical databases. We compared search results from a PICO (patients, intervention, comparison, outcome) framework for questions using different combinations of PICO elements. We also compared outcomes from doing searches using text words, Medical Subject Headings (MeSH), or a combination of both. All searches were documented using screenshots and saved search strategies.
RESULTS: Answers to all 6 questions using the PICO framework were found. A higher number of systematic reviews were obtained using a 2 PICO element search compared to a 4 element search. A more optimal choice of search is a combination of both text words and MeSH terms. Despite searching using the Systematic Review filter, many non-systematic reviews or narrative reviews were found in PubMed. There was poor overlap between outcomes of searches using different databases. The duration of search and screening for the 6 questions ranged from 1 to 4 hours.
CONCLUSION: This strategy has been shown to be feasible and can provide evidence to doctors' clinical questions. It has the potential to be incorporated into an interventional study to determine the impact of an online evidence retrieval system.
Fulltext Rural doctors' views on and experiences with evidence-based medicine: The FrEEDoM qualitative study

Hisham R, Liew SM, Ng CJ, Mohd Nor K, Osman IF, Ho GJ, et al.

PLoS One, 2016;11(3):e0152649.
PMID: 27031700 DOI: 10.1371/journal.pone.0152649

BACKGROUND: Evidence-based medicine is the integration of individual clinical expertise, best external evidence and patient values which was introduced more than two decades ago. Yet, primary care physicians in Malaysia face unique barriers in accessing scientific literature and applying it to their clinical practice.
AIM: This study aimed to explore the views and experiences of rural doctors' about evidence-based medicine in their daily clinical practice in a rural primary care setting.
METHODS: Qualitative methodology was used. The interviews were conducted in June 2013 in two rural health clinics in Malaysia. The participants were recruited using purposive sampling. Four focus group discussions with 15 medical officers and three individual in-depth interviews with family medicine specialists were carried out. All interviews were conducted using a topic guide and were audio-recorded, transcribed verbatim, checked and analyzed using a thematic approach.
RESULTS: Key themes identified were: (1) doctors viewed evidence-based medicine mainly as statistics, research and guidelines, (2) reactions to evidence-based medicine were largely negative, (3) doctors relied on specialists, peers, guidelines and non-evidence based internet sources for information, (4) information sources were accessed using novel methods such as mobile applications and (5) there are several barriers to evidence-based practice, including doctor-, evidence-based medicine-, patient- and system-related factors. These included inadequacies in knowledge, attitude, management support, time and access to evidence-based information sources. Participants recommended the use of online services to support evidence-based practice in the rural settings.
CONCLUSION: The level of evidence-based practice is low in the rural setting due to poor awareness, knowledge, attitude and resources. Doctors use non-evidence based sources and access them through new methods such as messaging applications. Further research is recommended to develop and evaluate interventions to overcome the identified barriers.
Study site: Klinik Kesihatan, Malaysia